1. Field of the Invention
The present invention relates to a sheet-feeding apparatus for feeding sheets to image forming apparatus such as copying machines, laser printers and plain paper facsimiles and to an image forming apparatus thereof, and more particularly to a sheet-feeding apparatus having improved sheet-feeding cassettes and sheet take-out section thereof and to an image forming apparatus having multifunctions such as multiple printing, double-face printing or the like.
2. Description of Related Art
Heretofore, cassettes used for image-forming apparatus such as copying machines and laser printers to store sheets have been mounted to the apparatus assembly in such a manner that the front end thereof is inserted into a sheet-feeding opening provided to a lateral side of the apparatus assembly and the rear end thereof is protruded beyond the apparatus assembly. Accordingly, the installation space occupied by the apparatus assembly becomes larger by the size of the cassette protrusion.
With the increased recent office automation, the multifunctioning of image forming apparatus has been required such as enlargement, reduction, continuous-page printing, double-face printing and multiple printing. With the increased multifunctioning of image forming apparatus, cassettes having different sheet-storing directions have been required even for the sheets with same size, and the kinds of the size of sheets to be handled are increased, thereby increasing the number of cassettes.
On the other hand, the effective utilization of office floor space has become an important issue, whereby image forming apparatus have been required to have a small installation space in order to save floor and work space.
As a copying machine which reduces installation space and is capable of mounting many cassettes to the machine assembly thereof, a front loading-type copying machine has been developed. In the machine, a plurality of cassettes storing sheets has been mounted to the lower side of the machine assembly in a manner to be taken out of the front, whereby the cassettes do not protrude beyond the machine assembly to minimize the installation area of the machine assembly.
However, an increased number of cassettes mounted in the front loading-type copying machine requires a large space for mounting within the machine assembly. This causes the copying machine to become large and the incorporation of functions used for multiple copying and double-face copying as elements of multifunctioning to become difficult. This interferes with the multifunctioning and systematizing of copying machines. Where all cassettes cannot be mounted in the machine assembly, another space to place some of them becomes necessary thereby installation space. Where some cassettes are placed outside the machine assembly, the exchange of the cassettes mounted in the machine assembly with those placed separately becomes annoying.
The mounting of cassettes in the machine assembly results in the elimination of the space for placing consumables such as sheets and toners previously placed in the lower part of the machine assembly, thereby requiring a new space for them.
In addition, generally, in the front loading-type copying machine, considering the interchangeability in the machine assembly, one size of sheet has been stored in one cassette whose size is of certain dimensions regardless of the size and kind of sheets. As a result, prior art cassettes have a size such that A-3 size sheets can be longitudinally placed with the longer size of sheet taken as the feeding direction, in the case where A-4 size sheets are laterally placed, approximately half of the space in the cassette becomes wasted (dead space) to cause an extremely large loss with respect to the effective utilization of space.